Clock skew alert

SQL Server performance monitoring and alerting

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Clock skew alert

Postby xdai » Tue Jan 22, 2013 4:37 pm

Hi,

we are currently on latest version of sql monitor, i would like to know what clock skew alert is about? thanks
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Postby Chris Spencer » Wed Jan 23, 2013 9:59 am

Hi

This alert will be raised when the difference between the Base Monitor clock time and the monitored server clock time is greater than fifteen seconds.

This is important because large time differences between machines can cause authentication issues which will prevent our software monitoring correctly.

I hope this helps

Regards
Chris
Chris Spencer
Test Engineer
Red Gate
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Postby xdai » Wed Jan 23, 2013 5:37 pm

Hi,

I do see the servers threw the alert has the same time as the base monitor server. thanks
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Re: Clock skew alert

Postby tristans » Thu Mar 21, 2013 8:04 pm

xdai wrote:Hi,

we are currently on latest version of sql monitor, i would like to know what clock skew alert is about? thanks


I'm getting the same message every day at seemingly random times. My base monitor and SQL server are the same machine so I don't see how this can even be possible. Can you please advise on how to fix this alert?
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Re: Clock skew alert

Postby Chris Spencer » Tue Apr 02, 2013 11:31 am

tristans wrote:I'm getting the same message every day at seemingly random times. My base monitor and SQL server are the same machine so I don't see how this can even be possible. Can you please advise on how to fix this alert?


First of all, apologies for the very late reply.

This does sound a bit crazy. Can you confirm that the SQL Server you mention is the server you are monitoring as opposed to the server that hosts the SQL Monitor data repository?

Regards
Chris
Chris Spencer
Test Engineer
Red Gate
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Postby Tradebridge_DBA's » Wed May 15, 2013 12:03 pm

Is there a way to change the clock skew alert to to either higher or lower value...?


regards,

Ian
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Postby priyasinha » Wed May 15, 2013 2:12 pm

Hi Ian,

No, it is not currently supported.

Thanks,
Priya
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Re: Clock skew alert

Postby Lynchie435 » Wed May 29, 2013 5:04 pm

tristans wrote:
xdai wrote:Hi,

we are currently on latest version of sql monitor, i would like to know what clock skew alert is about? thanks


I'm getting the same message every day at seemingly random times. My base monitor and SQL server are the same machine so I don't see how this can even be possible. Can you please advise on how to fix this alert?


I echo Tristan here, I also seem to be getting the message at seemingly random times and both the Base Monitor and Data Repository are on the same server.

Regards,

James
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Postby JoeGT » Sun Jun 09, 2013 10:36 pm

I have exactly the same situation and raised a ticket with Red Gate support who have spent a fair amount if time investigating :

http://www.red-gate.com/MessageBoard/vi ... clock+skew

However still no resolution.

I am monitoring 14 instances and 10 of them (only the ones that are member of an SQL cluster), continue to get these alerts multiple times a day.

One of the suggestions from Red Gate support was that the query of the instance for clock time takes too long to return a result and so the clock skew is actually a false positive.

I am loathe to turn this alert off as then if there was a genuine reason for actual clock skew, I would probably only know when I started to see other issues resulting from a lack of clock synchronization between my various servers.
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Postby Micke » Wed Jun 12, 2013 6:16 am

We also have this problem with all of our monitored servers, 14 physical hosts running failover cluster instances and one stand alone server. All servers including the one running SQL Monitor are physical.

The alert gets triggered at different frequencies, from around every 4-5 minutes on some machines to just a few per day on others. I have compared the Windows clock on the monitored servers with the server running SQL monitor and they do not differ more than 1 second, but the alerts reports up to 50 seconds of time difference.

All clock skew alerts get automatically ended the next minute, for example:
Time raised: 12 Jun 2013 6:23 AM
Time ended: 12 Jun 2013 6:24 AM

Is the clock skew check a WMI call or SQL query?

Servers are running SQL 2008R2 SP1 or SQL 2012 RTM, all on Windows 2008 R2 SP1.
SQL Monitor version 3.4.0.392.

Regards,
Michael
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